Exercise Physiology Questions and Answers

Answer: A

The condition is ischemia.

Ischemia is a local and usually temporary shortage of blood supply to a tissue, most often from narrowing or contraction (spasm) of the artery supplying it. Myocardial ischemia, for example, causes the chest pain of angina when the heart muscle gets too little blood during exertion.

Insulin is a hormone, not a condition. Hemolysis is the rupture of red blood cells, and hematuria is the presence of blood in the urine.

Answer: C

The predicted maximum heart rate is 220 - age.

The common rule estimates maximum heart rate as 220 minus age in years:

\[ HR_{max} = 220 - \text{age} \]

For a 20-year-old this gives 200 beats per minute. It is used to set training zones, such as 60 to 85 percent of maximum, and in the Karvonen formula for target heart rate. Individual values can differ from it by 10 beats or more.

100 - age and 120 - age give values far too low to be a maximum, and height in cm minus 100 is Broca's index for ideal body weight, not a heart rate formula.

Answer: D

The rupture of red blood cells is hemolysis.

Hemolysis (from haemo, blood, and lysis, breaking) is the breakdown of red blood cells with release of their haemoglobin into the plasma. In athletes it can occur as 'foot-strike haemolysis' in long-distance runners.

Haemoglobin is the oxygen-carrying protein inside red cells, not a process. Hemodilution is the dilution of blood by an increase in plasma volume, as happens with endurance training. Hematuria is blood in the urine.

Answer: C

A lack of sufficient red blood cells or haemoglobin is anemia.

Anemia reduces the oxygen-carrying capacity of the blood, causing fatigue, breathlessness and poor endurance. Iron deficiency is the commonest cause, and athletes, especially women, are at risk.

An aneurysm is a balloon-like swelling of a weakened artery wall. An androgen is a male sex hormone such as testosterone. Apnea is a temporary stopping of breathing, as in sleep apnoea.

Answer: D

The clot is an embolus.

An embolus is a clot, or other mass such as fat or air, that breaks loose and travels in the bloodstream until it lodges in a vessel too narrow to let it pass, blocking the circulation there (embolism). A clot from the leg veins that lodges in the lungs is a pulmonary embolism.

Osmosis and diffusion are processes by which water and solutes move across membranes, and dyspnea is difficult or laboured breathing. None of them is a travelling clot.

Answer: B

It stands for the arterial-mixed venous oxygen difference.

This is the Fick equation:

\[ \begin{aligned} \dot{V}O_{2} &= SV \times HR \\ &\quad \times (a - \bar{v})O_{2}\ \text{diff} \end{aligned} \]

Stroke volume times heart rate is cardiac output, and the a-v̄ O₂ difference is the difference in oxygen content between arterial blood and mixed venous blood, the blood returning from all the tissues, which is what the bar over the v denotes. It measures how much oxygen the tissues extract.

Options A, C and D drop the 'mixed venous' part, which is what the symbol v̄ specifies, or give terms that do not describe a difference between arterial and venous oxygen content.

Answer: B

Static lung volumes cannot predict exercise performance.

Static lung volumes, such as vital capacity, tidal volume and residual volume, are measured at rest. They depend largely on body size, age and sex, and in healthy people they are not a limiting factor in exercise, since ventilation can rise far more than the oxygen transport system needs.

So athletes and untrained people of the same size have similar static lung volumes, and these values do not predict endurance performance. Statements that they are larger for the untrained or lower for the trained are therefore wrong.

Answer: B

The sarcoplasmic reticulum stores calcium.

The sarcoplasmic reticulum is a network of membranes around each myofibril in a muscle fibre. When a nerve impulse reaches the fibre, it releases calcium ions into the sarcoplasm. Calcium binds to troponin, which moves tropomyosin away from the binding sites on actin, so the myosin heads can attach and the muscle contracts. Calcium is then pumped back into the reticulum and the muscle relaxes.

Potassium is involved in the nerve and muscle action potential but is held in the cell fluid, not stored in the reticulum. Iron is in myoglobin, and copper has no role in contraction.

Answer: B

Fatigue at the neuromuscular junction is due to decreased release of Acetylcholine.

At the neuromuscular junction the motor nerve ending releases the neurotransmitter acetylcholine, which excites the muscle fibre. With repeated high-frequency stimulation the nerve terminal can run short of acetylcholine, so transmission fails: this is neuromuscular (junctional) fatigue.

The other options act inside the muscle fibre, not at the junction. Calcium is released from the sarcoplasmic reticulum to start contraction, and hydrogen ions and lactic acid accumulate during intense anaerobic work and cause muscular fatigue.

Answer: A

The greatest DOMS follows Eccentric exercise.

Delayed onset muscle soreness peaks 24-72 hours after unaccustomed exercise. It is caused by micro-damage to muscle fibres and connective tissue, which is greatest in eccentric contractions, where the muscle lengthens while producing force, as in running downhill or lowering a weight.

Concentric (shortening), isometric (static) and isokinetic (constant-speed) contractions put less mechanical strain on each fibre, so they cause much less soreness.